408 SPIRORBIS GRANULATUS. 
several forms, e.g., S. granulatus, Fabricius, 1780 = wolaceus, Levinsen, 1883; S. granulatus, 
Montagu, 1807 = sulcatus, Adams, 1797, S. granulatus, Langerhans, 1880, and probably that 
of De St. Joseph, 1894, and militaris, Claparéde, 1868 ; S. granulatus, Caullery and Mesnil, 
1897=Sp. granulatus, Moore, 1902=trianeular form of Sp. quadrangularis, Stimpson, 
1853. She states that ‘the tubes of the adult' are sinistral, with a deep groove on the 
top of the whorls, a large rounded carina on each side, the inner defining the small central 
cavity. In large specimens a shallower groove occurs on the side of the whorl, and a smaller 
carina along its lower edge. It is much longer and thicker than the dextral tricarinate S. 
heterostrophus, and must take the name sulcatus, Adams.” 
Percy Moore’s’ Spirorbis granulata, var. tridentata, Levinsen, is a species with three 
discs in front of the brood-sac in the operculum, and therefore differs from the present 
species. 
Fauvel (1914) apparently follows Caullery and Mesnil in the discrimination of S. 
granulatus, his form also incubating in its operculum, and being found at the surface 
on sea-weeds in the Sargasso Sea, as well as on the shore at Grande Salvage. 
A recent notice (1917)-of S. granulata, L., by Folke Borg® takes for granted that all 
authors refer to the type with the opercular brood-pouch, whereas comparatively few have 
dealt with this form. It may be, however, that such a differentiation is not specific, and 
the experience of Falograna would lead to caution m drawing conclusions without a more 
searching inquiry into the subject. So far as the published accounts and figures go there 
is marked divergence, amonest other features, in the operculum. 
A Spirorbis is not uncommon on the under-surface of stones in Guernsey and Herm, 
in which, whilst the tube and other parts are indistinguishable, the collar-bristles do not show 
the marked distinction between the coarse serrations of the basal web and the fine serrations 
of the distal blade. Moreover, in certain examples the distal portion of the blade had coarser 
serrations than those usually seen in S. granulatus. The sickle-shaped bristles have the 
distal region broad and curved, with coarse serrations on the tapering part. The tube 
resembles that of Spirorbis granulatus in being coiled from right to left—that is, from the 
umbilicus or origin, and cannot be distinguished from it. It presents three ridges and two 
grooves on the free surface, and in some a slight degree of crenation of the ridges—a feature, 
however, better marked in Sp. granulatus. The aperture is circular, with the ends of two 
of the ridges projecting prominently above it. The operculum is comparatively thin and 
flat, with the external (calcareous) surface shgehtly hollowed out, and with a stalk which 
widens out superiorly to the full breadth of the disc. Moreover, the ova seem to be 
developed in the operculum. 
A variety of S. granulatus comes from Cliff Sound, Scalloway, in which the branchie 
differ from the typical form at St. Andrews in the comparative stoutness of the filaments, 
and the diminution in the length of the distal pinne, so that the thick terminal process at 
the end of each filament becomes prominent, whereas in the examples from St. Andrews the 
long distal pinnee obscure the slender terminal process. ‘The operculum (Plate CXXII, fig. 8) 
differs little from that of the typical form, except that it tapers more abruptly inferiorly. 
! On Haliotis, Guernsey, and limpet, Birterbury Bay, Ireland (Bush). 
* “Proc. Acad. Nat. Sc. Philad.,’ p. 362. 
5 “Zool. Bidrag. Uppsala,’ Bd. v, p. 28. 
